The Bord Gáis Energy index saw its biggest monthly increase since February last month on the back of rising oil and gas prices.

The index rose to stand at 144 in July, up from June's reading of 133. The index is 4% higher than the same time last year.

A seasonally adjusted index designed to measure prices in the wholesale energy market, the Bord Gáis Energy index tracks oil, gas, coal and electricity prices.

It combines these into one index that provides an overall indication of the global performance of the energy sector.

Bord Gáis said wholesale oil prices rose on supply concerns and expectations of more economic stimulus measures to overcome global weakness in July. The continuing weakness of the euro also played a significant role in the monthly rise, the company said.

The oil element of the index rose by 10% to 157 in July as the price of a barrel of oil rose 10% in euro terms month-on-month due to growing geopolitical tensions in the Middle East and on increased expectations of stimulus plans from the governing authorities in Europe, China and the US.

Bord Gáis said the natural gas element of its index increased by 4% to 201 with most of the rise down to the ongoing weakness of the euro compared to sterling.

Ireland buys its gas on the wholesale markets in the UK and a weakening euro makes those buys more expensive. A threatened strike by Norwegian energy companies also put pressure on prices.

The coal element of the index was up 12% to 131 with European coal prices seeing dramatic increases due to a rail strike in Columbia. The majority of Columbia's coal exports are shipped to Europe and Ireland imports most of its coal from there. Bord Gáis noted that the price rise could prove temporary in nature when the strike is resolved.

The index's electricity element was up 2% to 113 in July. Bord Gáis said that as most of the electricity produced here is generated by burning gas, the 4% rise in gas prices put upward pressure on the cost of producing electricity. Higher coal prices also pushed electricity costs higher.

John Heffernan, a power trader at Bord Gáis Energy said that in July we saw the vulnerability of fuel commodity prices to threats in global supplies or supply failures. He said that a combination of industrial action in Norway and Columbia, along with escalating tensions in the Middle East, pushed prices higher.

''The euro performed poorly against its rivals during the month and lost more ground to the US dollar and British pound, which impacted negatively on euro zone commodity buyers,'' he added.